Fluorocarbon polymers are extensively used in the textile industry to impart oleophobicity/oil repellency to a fabric. For example, U.S. Pat. No. 5,247,008 describes finishing agents for textiles, leather, paper and mineral substrates which are aqueous dispersions of a copolymer of a perfluoroalkyl acrylate or methacrylate, an alkyl acrylate or methacrylate and an aminoalkyl acrylate or methacrylate.
U.S. Pat. No. 5,068,295 describes a water and oil repellent comprising a copolymer of a perfluoroalkyl acrylate or methacrylate, a polyorganosiloxane containing a vinyl group and a vinyl monomer containing an isocyanate or blocked isocyanate group.
U.S. Pat. No. 6,582,620 and U.S. Pat. No. 5,883,185 describe a treating composition for textiles to render them water and oil repellent obtained by cohydrolysis and condensation of (A) a fluorinated alkyl-bearing alkoxysilane, (B) an amino-bearing alkoxysilane, and (C) an alkoxysilyl-bearing polyorganosiloxane.
U.S. Pat. No. 5,536,304 describes application of a blend of a succinic anhydride-terminated polydimethylsiloxane and a poly(fluoroalkyl methacrylate) to cotton to give a fabric with oil repellency.
U.S. Pat. No. 6,472,019 describes treating a textile with a water- and oil-repellent agent comprising a fluorine-containing polymer and a sulphated fatty acid compound and WO 2004/069935 and WO 2004/069955 describe a fluorine containing polymer delivered as an aqueous dispersion for textile treatment.
One of the major disadvantages of topical finishes prepared with fluorocarbon polymers is that they impart a harsh feel to the fabric surface. There is a need for textile treatment agents which impart oleophobicity and oil repellency to fabrics without imparting a harsh feel to the fabric surface, and preferably whilst at the same time imparting an improvement in feel compared to untreated fabric.
Hitherto, in order to give both water- and oil-repellency and softness to a substrate such as a textile, a water- and oil-repellent composition comprising a perfluoroalkyl group giving water- and oil-repellency and a silicone compound giving softness has been widely used. Please see, for example, JP-A-58-42682, JP-A-60-190408, JP-A-63-075082, JP-A-09-143877, and U.S. Pat. No. 4,070,152.
There is, for example, a method of using a copolymer of a fluorine-containing acrylate monomer and a silicone acrylate monomer for the same purpose (for example, JP-A-02-214791 and JP-A-03-231986). This method, however, has the problem that the water- and oil-repellency is decreased.
By the way, the fluoroacrylate polymer used as the conventional surface treatment agent needs at least 8 carbon atoms in the fluoroalkyl group so as to give sufficient water- and oil-repellency. Since said fluoroacrylate polymer has high hydrophobicity, in the case of emulsion polymerization, there are necessity that the amount of the used emulsifier is large, the problem that the type of the emulsifier is limited, and the necessity that an aid solvent should be used due to poor compatibility with another fluorine-free monomer. In the case of a solution polymerization, there is the problem that the solubility into a polymerization solvent is decreased for the same reason.
Recent study results (EPA Report “PRELIMINARY RISK ASSESSMENT OF THE DEVELOPMENTAL TOXICITY ASSOCIATED WITH EXPOSURE TO PERFLUOROOCTANOIC ACID AND ITS SALTS” (http://www.epa.gov/opptintr/pfoa/pfoara.pdf)) and the like clarify that a PFOA (perfluorooctanoic acid) doubtfully has a potential risk of environmental load. EPA (Environmental Protection Agency of USA) announced on Apr. 14, 2003 that the EPA intensifies the scientific investigation.
On the other hand, Federal Register (FR Vol. 68, No. 73/Apr. 16, 2003 [FRL-2303-8]) (http://www.epa.gov/opptintr/pfoa/pfoafr.pdf), EPA Environmental News for release Monday April, 2003 “EPA INTENSIFIES SCIENTIFIC INVESTIGATION OF A CHEMICAL PROCESSING AID” (http://www.epa.gov/opptintr/pfoa/pfoaprs.pdf), and EPA OPPT FACT SHEET Apr. 14, 2003 (http://www.epa.gov/opptintr/pfoa/pfoafacts.pdf) announced that a fluorinated “telomer” may metabolize or decompose to PFOA. It is also announced that the telomer is used in a large number of commercial products including fire fighting foams, care products and cleaning products as well as soil, stain and grease resistant coating on carpets, textiles, paper, and leather.
Various recent research results indicate that in view of the practical treatment of fibers with the surface treatment agent (particularly the water- and oil-repellent agent), the important surface property is not a static contact angle, but is a dynamic contact angle, particularly a reversing contact angle. That is, the advancing contact angle of water is not dependent on the carbon number of the fluoroalkyl side chain, but the reversing contact angle of water in the case of carbon number of at most 7 is remarkably low than that in the case of carbon number of at least 8. In correspondence to this, an X ray analysis shows that the side chain crystallizes when the carbon number of side chain is at least 7. It is known that the actual water repellency has relationship with the crystallization of the side chain and that mobility of the surface treatment agent molecules is an important factor for expression of the actual performances (for example, MAEKAWA takashige, FINE CHEMICAL, Vol. 23, No. 6, page 12 (1994)). Accordingly, it is believed that the acrylate polymer having low carbon number of fluoroalkyl group in the side chain which is at most 7 (particularly at most 6) has low crystallinity so that the polymer cannot satisfy the actual performances (particularly water repellency).
Hitherto, it is know that the fluorine-containing acrylate polymer having an alpha position substituted with fluorine, chlorine or the like has good adhesion to a substrate, forms a film having a large strength, and imparts good water- and oil-repellency (JP-A-63-90588, JP-A-63-99285 and JP-A-01-315471). These publications also show that the carbon number of the fluoroalkyl group used in working examples is at least 8, and these publications do not think the use of the acrylate monomer having fluoroalkyl group having at most 6 carbon atoms.
It is proposed to use the fluorine-containing acrylate polymer which has the fluoroalkyl group having at most 4 carbon atoms and in which the alpha position is substituted with fluorine, chlorine or the like (for example, WO2004-096939). Since the polymer film, however, is strong, the feeling of the treated textile is problematically deteriorated.
A method of adding a silicone polymer or copolymerizing a silicon-containing monomer is proposed for the fluoroalkyl alkyl group having at most 4 carbon atoms to give both good water- and oil-repellency and feeling (for example, WO2004-108855). The increase of the silicone polymer content, however, problematically decreases the water- and oil-repellency.